This study in basic cancer biology is directed toward the following topics: 1. Enzyme structure function and regulation - Glutamate dehydrogenase will be labeled covalently in the catalytic and regulatory (allosteric) binding sites. The relationships between changes in these sites and catalytic and regulatory properties. 2. Drug nucleic acid interactions and their role in regulating mutations and mutation repair. For example, a variety of mutagens and their non-mutagenic analogs will be studied both for their biological effects and their direct effects on nucleic acids and nucleic acid enzymes. 3. DNA repair and cancer biology. Repair will be studied in relation to carcinogenesis and genotoxic cancer therapy in terms of inhibitor specificity and mechanism distribution of repair in the genome, and repair of extra nuclear DNA.